class A:
    def __init__(self):
        print('A')


class B(A):
    def __init__(self):
        super().__init__()
        print('B')


class C(A):
    def __init__(self):
        super().__init__()
        print('C')


class D(B, C):
    def __init__(self):
        super().__init__()
        print('D')


if __name__ == '__main__':
    d = D()
    print(D.mro())